Lightroom: "Limit file size to" on export is not working in LR4

Description to reproduce:
Trying to export the sample file as jpg with max. width of 600px and limit file size to 150k.

Current behavior:
Export will not be done. The error message "Could not create a JPEG that met your limit of 150k bytes" is shown.

Expected behavior:
JPEG quality should be automatically be adjusted to create a file with size of 150k or lower.

Manual export setting:
Doing manually the export without using "limit file size to" and setting quality to 80, the result is an file of 142k bytes. So reaching a file with correct size is absolutely possible.

This problem can be also reproduced on LR 4.1 RC1 and 2.
Seams that only files with hight high white content are affected.

Please tryout the problem yourself with the sample file and promote for this bug.

If your image is too big to compress to your desired KB size as a jpg using quality 0 then lightroom will return the error that is stated above.

This happens because the restrict file size adjusts the quality of the jpg but does not adjust the actual image size.

If you have an image that is 2500 x 3000 pixels, even if you compress the image quality to quality 0 on the jpg image quality slider, the image may still be bigger than your desired file size of say 100 KB.

To fix this you need to play with your image size settings in the export field. If you adjust the image size to say 500 x 600 and then set the 'limit file size' to 100 KB you will most likely be able to get that image under 100 KB.

The file size of the image is affected by the size of the image (The pixel aspect ration) as well as the quality of the image.